A square footing with a size of 8 ft by 8 ft is to carry a total load of 40 kips. The depth of the footing is 5 ft below the ground surface, and groundwater is located at the ground surface. The subsoil consists of a uniform deposit of soft clay, the cohesion of which is 500 1b/ft 2. the soil's unit weight is 110 1b/ft 3. Compute the factor of safety against bearing capacity failure